--- demos/src/egl/opengles2/es2gears.c 2010-06-22 14:41:00.173055999 +0300 +++ demos-es2gears-refactor/src/egl/opengles2/es2gears.c 2010-07-13 17:29:22.784047996 +0300 @@ -23,18 +23,23 @@ * Ported to GLES2. * Kristian Høgsberg * May 3, 2010 + * + * Improve GLES2 port: + * * Refactor gear drawing. + * * Use correct normals for surfaces. + * * Improve shader. + * * Use perspective projection transformation. + * * Add FPS count. + * * Add comments. + * Alexandros Frantzis + * Jul 13, 2010 */ -/* - * Command line options: - * -info print GL implementation information - * - */ - - #define GL_GLEXT_PROTOTYPES #define EGL_EGLEXT_PROTOTYPES +#define _GNU_SOURCE + #include #include #include @@ -46,135 +51,239 @@ #include #include "eglut.h" +#define STRIPS_PER_TOOTH 7 +#define VERTICES_PER_TOOTH 34 +#define GEAR_VERTEX_STRIDE 6 + +/** + * Struct describing the vertices in triangle strip + */ +struct vertex_strip { + /** The first vertex in the strip */ + GLint first; + /** The number of consecutive vertices in the strip after the first */ + GLint count; +}; + +/* Each vertex consist of GEAR_VERTEX_STRIDE GLfloat attributes */ +typedef GLfloat GearVertex[GEAR_VERTEX_STRIDE]; + +/** + * Struct representing a gear. + */ struct gear { - GLfloat *vertices; + /** The array of vertices comprising the gear */ + GearVertex *vertices; + /** The number of vertices comprising the gear */ + int nvertices; + /** The array of triangle strips comprising the gear */ + struct vertex_strip *strips; + /** The number of triangle strips comprising the gear */ + int nstrips; + /** The Vertex Buffer Object holding the vertices in the graphics card */ GLuint vbo; - int count; }; -static GLfloat view_rotx = 20.0, view_roty = 30.0, view_rotz = 0.0; +/** The view rotation [x, y, z] */ +static GLfloat view_rot[3] = { 20.0, 30.0, 0.0 }; +/** The gears */ static struct gear *gear1, *gear2, *gear3; +/** The current gear rotation angle */ static GLfloat angle = 0.0; -static GLuint proj_location, light_location, color_location; -static GLfloat proj[16]; +/** The location of the shader uniforms */ +static GLuint ModelViewProjectionMatrix_location, + NormalMatrix_location, + LightSourcePosition_location, + MaterialColor_location; +/** The projection matrix */ +static GLfloat ProjectionMatrix[16]; +/** The direction of the directional light for the scene */ +static const GLfloat LightSourcePosition[4] = { 5.0, 5.0, 10.0, 1.0}; -static GLfloat * -vert(GLfloat *p, GLfloat x, GLfloat y, GLfloat z, GLfloat *n) +/** + * Fills a gear vertex. + * + * @param v the vertex to fill + * @param x the x coordinate + * @param y the y coordinate + * @param z the z coortinate + * @param n pointer to the normal table + * + * @return the operation error code + */ +static GearVertex * +vert(GearVertex *v, GLfloat x, GLfloat y, GLfloat z, GLfloat n[3]) { - p[0] = x; - p[1] = y; - p[2] = z; - p[3] = n[0]; - p[4] = n[1]; - p[5] = n[2]; - - return p + 6; -} - -/* Draw a gear wheel. You'll probably want to call this function when - * building a display list since we do a lot of trig here. - * - * Input: inner_radius - radius of hole at center - * outer_radius - radius at center of teeth - * width - width of gear - * teeth - number of teeth - * tooth_depth - depth of tooth + v[0][0] = x; + v[0][1] = y; + v[0][2] = z; + v[0][3] = n[0]; + v[0][4] = n[1]; + v[0][5] = n[2]; + + return v + 1; +} + +/** + * Create a gear wheel. + * + * @param inner_radius radius of hole at center + * @param outer_radius radius at center of teeth + * @param width width of gear + * @param teeth number of teeth + * @param tooth_depth depth of tooth + * + * @return pointer to the constructed struct gear */ static struct gear * -gear(GLfloat inner_radius, GLfloat outer_radius, GLfloat width, - GLint teeth, GLfloat tooth_depth) +create_gear(GLfloat inner_radius, GLfloat outer_radius, GLfloat width, + GLint teeth, GLfloat tooth_depth) { - GLint i; GLfloat r0, r1, r2; GLfloat da; - GLfloat *p, *v; + GearVertex *v; struct gear *gear; double s[5], c[5]; - GLfloat verts[3 * 14], normal[3]; - const int tris_per_tooth = 20; + GLfloat normal[3]; + int cur_strip = 0; + int i; + /* Allocate memory for the gear */ gear = malloc(sizeof *gear); if (gear == NULL) return NULL; + /* Calculate the radii used in the gear */ r0 = inner_radius; r1 = outer_radius - tooth_depth / 2.0; r2 = outer_radius + tooth_depth / 2.0; da = 2.0 * M_PI / teeth / 4.0; - gear->vertices = calloc(teeth * tris_per_tooth * 3 * 6, - sizeof *gear->vertices); - s[4] = 0; - c[4] = 1; + /* Allocate memory for the triangle strip information */ + gear->nstrips = STRIPS_PER_TOOTH * teeth; + gear->strips = calloc(gear->nstrips, sizeof (*gear->strips)); + + /* Allocate memory for the vertices */ + gear->vertices = calloc(VERTICES_PER_TOOTH * teeth, sizeof(*gear->vertices)); v = gear->vertices; + for (i = 0; i < teeth; i++) { - s[0] = s[4]; - c[0] = c[4]; + /* Calculate needed sin/cos for varius angles */ + sincos(i * 2.0 * M_PI / teeth, &s[0], &c[0]); sincos(i * 2.0 * M_PI / teeth + da, &s[1], &c[1]); sincos(i * 2.0 * M_PI / teeth + da * 2, &s[2], &c[2]); sincos(i * 2.0 * M_PI / teeth + da * 3, &s[3], &c[3]); sincos(i * 2.0 * M_PI / teeth + da * 4, &s[4], &c[4]); - normal[0] = 0.0; - normal[1] = 0.0; - normal[2] = 1.0; - - v = vert(v, r2 * c[1], r2 * s[1], width * 0.5, normal); - - v = vert(v, r2 * c[1], r2 * s[1], width * 0.5, normal); - v = vert(v, r2 * c[2], r2 * s[2], width * 0.5, normal); - v = vert(v, r1 * c[0], r1 * s[0], width * 0.5, normal); - v = vert(v, r1 * c[3], r1 * s[3], width * 0.5, normal); - v = vert(v, r0 * c[0], r0 * s[0], width * 0.5, normal); - v = vert(v, r1 * c[4], r1 * s[4], width * 0.5, normal); - v = vert(v, r0 * c[4], r0 * s[4], width * 0.5, normal); - - v = vert(v, r0 * c[4], r0 * s[4], width * 0.5, normal); - v = vert(v, r0 * c[0], r0 * s[0], width * 0.5, normal); - v = vert(v, r0 * c[4], r0 * s[4], -width * 0.5, normal); - v = vert(v, r0 * c[0], r0 * s[0], -width * 0.5, normal); - - normal[0] = 0.0; - normal[1] = 0.0; - normal[2] = -1.0; - - v = vert(v, r0 * c[4], r0 * s[4], -width * 0.5, normal); - - v = vert(v, r0 * c[4], r0 * s[4], -width * 0.5, normal); - v = vert(v, r1 * c[4], r1 * s[4], -width * 0.5, normal); - v = vert(v, r0 * c[0], r0 * s[0], -width * 0.5, normal); - v = vert(v, r1 * c[3], r1 * s[3], -width * 0.5, normal); - v = vert(v, r1 * c[0], r1 * s[0], -width * 0.5, normal); - v = vert(v, r2 * c[2], r2 * s[2], -width * 0.5, normal); - v = vert(v, r2 * c[1], r2 * s[1], -width * 0.5, normal); - - v = vert(v, r1 * c[0], r1 * s[0], width * 0.5, normal); - - v = vert(v, r1 * c[0], r1 * s[0], width * 0.5, normal); - v = vert(v, r1 * c[0], r1 * s[0], -width * 0.5, normal); - v = vert(v, r2 * c[1], r2 * s[1], width * 0.5, normal); - v = vert(v, r2 * c[1], r2 * s[1], -width * 0.5, normal); - v = vert(v, r2 * c[2], r2 * s[2], width * 0.5, normal); - v = vert(v, r2 * c[2], r2 * s[2], -width * 0.5, normal); - v = vert(v, r1 * c[3], r1 * s[3], width * 0.5, normal); - v = vert(v, r1 * c[3], r1 * s[3], -width * 0.5, normal); - v = vert(v, r1 * c[4], r1 * s[4], width * 0.5, normal); - v = vert(v, r1 * c[4], r1 * s[4], -width * 0.5, normal); - - v = vert(v, r1 * c[4], r1 * s[4], -width * 0.5, normal); + /* A set of macros for making the creation of the gears easier */ +#define GEAR_POINT(r, da) { (r) * c[(da)], (r) * s[(da)] } +#define SET_NORMAL(x, y, z) do { \ + normal[0] = (x); normal[1] = (y); normal[2] = (z); \ +} while(0) + +#define GEAR_VERT(v, point, sign) vert((v), p[(point)].x, p[(point)].y, (sign) * width * 0.5, normal) + +#define START_STRIP do { \ + gear->strips[cur_strip].first = v - gear->vertices; \ +} while(0); + +#define END_STRIP do { \ + int _tmp = (v - gear->vertices); \ + gear->strips[cur_strip].count = _tmp - gear->strips[cur_strip].first; \ + cur_strip++; \ +} while (0) + +#define QUAD_WITH_NORMAL(p1, p2) do { \ + SET_NORMAL((p[(p1)].y - p[(p2)].y), -(p[(p1)].x - p[(p2)].x), 0); \ + v = GEAR_VERT(v, (p1), -1); \ + v = GEAR_VERT(v, (p1), 1); \ + v = GEAR_VERT(v, (p2), -1); \ + v = GEAR_VERT(v, (p2), 1); \ +} while(0) + + struct point { + GLfloat x; + GLfloat y; + }; + + /* Create the 7 points (only x,y coords) used to draw a tooth */ + struct point p[7] = { + GEAR_POINT(r2, 1), // 0 + GEAR_POINT(r2, 2), // 1 + GEAR_POINT(r1, 0), // 2 + GEAR_POINT(r1, 3), // 3 + GEAR_POINT(r0, 0), // 4 + GEAR_POINT(r1, 4), // 5 + GEAR_POINT(r0, 4), // 6 + }; + + /* Front face */ + START_STRIP; + SET_NORMAL(0, 0, 1.0); + v = GEAR_VERT(v, 0, +1); + v = GEAR_VERT(v, 1, +1); + v = GEAR_VERT(v, 2, +1); + v = GEAR_VERT(v, 3, +1); + v = GEAR_VERT(v, 4, +1); + v = GEAR_VERT(v, 5, +1); + v = GEAR_VERT(v, 6, +1); + END_STRIP; + + /* Inner face */ + START_STRIP; + QUAD_WITH_NORMAL(4, 6); + END_STRIP; + + /* Back face */ + START_STRIP; + SET_NORMAL(0, 0, -1.0); + v = GEAR_VERT(v, 6, -1); + v = GEAR_VERT(v, 5, -1); + v = GEAR_VERT(v, 4, -1); + v = GEAR_VERT(v, 3, -1); + v = GEAR_VERT(v, 2, -1); + v = GEAR_VERT(v, 1, -1); + v = GEAR_VERT(v, 0, -1); + END_STRIP; + + /* Outer face */ + START_STRIP; + QUAD_WITH_NORMAL(0, 2); + END_STRIP; + + START_STRIP; + QUAD_WITH_NORMAL(1, 0); + END_STRIP; + + START_STRIP; + QUAD_WITH_NORMAL(3, 1); + END_STRIP; + + START_STRIP; + QUAD_WITH_NORMAL(5, 3); + END_STRIP; } - gear->count = (v - gear->vertices) / 6; + gear->nvertices = (v - gear->vertices); + /* Store the vertices in a vertex buffer object (VBO) */ glGenBuffers(1, &gear->vbo); glBindBuffer(GL_ARRAY_BUFFER, gear->vbo); - glBufferData(GL_ARRAY_BUFFER, gear->count * 6 * 4, - gear->vertices, GL_STATIC_DRAW); + glBufferData(GL_ARRAY_BUFFER, gear->nvertices * sizeof(GearVertex), + gear->vertices, GL_STATIC_DRAW); return gear; } +/** + * Multiplies two 4x4 matrices. + * + * The result is stored in matrix m. + * + * @param m the first matrix to multiply + * @param n the second matrix to multiply + */ static void multiply(GLfloat *m, const GLfloat *n) { @@ -189,11 +298,20 @@ row = n + d.quot * 4; column = m + d.rem; for (j = 0; j < 4; j++) - tmp[i] += row[j] * column[j * 4]; + tmp[i] += row[j] * column[j * 4]; } memcpy(m, &tmp, sizeof tmp); } +/** + * Rotates a 4x4 matrix. + * + * @param[in,out] m the matrix to rotate + * @param angle the angle to rotate + * @param x the x component of the direction to rotate to + * @param y the y component of the direction to rotate to + * @param z the z component of the direction to rotate to + */ static void rotate(GLfloat *m, GLfloat angle, GLfloat x, GLfloat y, GLfloat z) { @@ -210,6 +328,15 @@ multiply(m, r); } + +/** + * Translates a 4x4 matrix. + * + * @param[in,out] m the matrix to translate + * @param x the x component of the direction to translate to + * @param y the y component of the direction to translate to + * @param z the z component of the direction to translate to + */ static void translate(GLfloat *m, GLfloat x, GLfloat y, GLfloat z) { @@ -218,98 +345,240 @@ multiply(m, t); } -static const GLfloat light[3] = { 1.0, 1.0, -1.0 }; - +/** + * Creates an identity 4x4 matrix. + * + * @param m the matrix make an identity matrix + */ +static void +identity(GLfloat *m) +{ + GLfloat t[16] = { + 1.0, 0.0, 0.0, 0.0, + 0.0, 1.0, 0.0, 0.0, + 0.0, 0.0, 1.0, 0.0, + 0.0, 0.0, 0.0, 1.0, + }; + + memcpy(m, t, sizeof(t)); +} + +/** + * Transposes a 4x4 matrix. + * + * @param m the matrix to transpose + */ +static void +transpose(GLfloat *m) +{ + GLfloat t[16] = { + m[0], m[4], m[8], m[12], + m[1], m[5], m[9], m[13], + m[2], m[6], m[10], m[14], + m[3], m[7], m[11], m[15]}; + + memcpy(m, t, sizeof(t)); +} + +/** + * Inverts a 4x4 matrix. + * + * This function can currently handle only pure translation-rotation matrices. + * Read http://www.gamedev.net/community/forums/topic.asp?topic_id=425118 + * for an explanation. + */ static void -draw_gear(struct gear *gear, GLfloat *m, - GLfloat x, GLfloat y, GLfloat angle, const GLfloat *color) +invert(GLfloat *m) +{ + GLfloat t[16]; + identity(t); + + // Extract and invert the translation part 't'. The inverse of a + // translation matrix can be calculated by negating the translation + // coordinates. + t[12] = -m[12]; t[13] = -m[13]; t[14] = -m[14]; + + // Invert the rotation part 'r'. The inverse of a rotation matrix is + // equal to its transpose. + m[12] = m[13] = m[14] = 0; + transpose(m); + + // inv(m) = inv(r) * inv(t) + multiply(m, t); +} + +/** + * Calculate a perspective projection transformation. + * + * @param m the matrix to save the transformation in + * @param fovy the field of view in the y direction + * @param aspect the view aspect ratio + * @param zNear the near clipping plane + * @param zFar the far clipping plane + */ +void perspective(GLfloat *m, GLfloat fovy, GLfloat aspect, GLfloat zNear, GLfloat zFar) { GLfloat tmp[16]; + identity(tmp); + + double sine, cosine, cotangent, deltaZ; + GLfloat radians = fovy / 2 * M_PI / 180; + + deltaZ = zFar - zNear; + sincos(radians, &sine, &cosine); + + if ((deltaZ == 0) || (sine == 0) || (aspect == 0)) + return; - memcpy(tmp, m, sizeof tmp); - translate(tmp, x, y, 0); - rotate(tmp, 2 * M_PI * angle / 360.0, 0, 0, 1); - glUniformMatrix4fv(proj_location, 1, GL_FALSE, tmp); - glUniform3fv(light_location, 1, light); - glUniform4fv(color_location, 1, color); + cotangent = cosine / sine; + tmp[0] = cotangent / aspect; + tmp[5] = cotangent; + tmp[10] = -(zFar + zNear) / deltaZ; + tmp[11] = -1; + tmp[14] = -2 * zNear * zFar / deltaZ; + tmp[15] = 0; + + memcpy(m, tmp, sizeof(tmp)); +} + +/** + * Draws a gear. + * + * @param gear the gear to draw + * @param transform the current transformation matrix + * @param x the x position to draw the gear at + * @param y the y position to draw the gear at + * @param angle the rotation angle of the gear + * @param color the color of the gear + */ +static void +draw_gear(struct gear *gear, GLfloat *transform, + GLfloat x, GLfloat y, GLfloat angle, const GLfloat color[4]) +{ + GLfloat model_view[16]; + GLfloat normal_matrix[16]; + GLfloat model_view_projection[16]; + + /* Translate and rotate the gear */ + memcpy(model_view, transform, sizeof (model_view)); + translate(model_view, x, y, 0); + rotate(model_view, 2 * M_PI * angle / 360.0, 0, 0, 1); + + /* Create and set the ModelViewProjectionMatrix */ + memcpy(model_view_projection, ProjectionMatrix, sizeof(model_view_projection)); + multiply(model_view_projection, model_view); + + glUniformMatrix4fv(ModelViewProjectionMatrix_location, 1, GL_FALSE, + model_view_projection); + + /* + * Create and set the NormalMatrix. It's the inverse transpose of the + * ModelView matrix. + */ + memcpy(normal_matrix, model_view, sizeof (normal_matrix)); + invert(normal_matrix); + transpose(normal_matrix); + glUniformMatrix4fv(NormalMatrix_location, 1, GL_FALSE, normal_matrix); + + /* Set the gear color */ + glUniform4fv(MaterialColor_location, 1, color); + + /* Set the vertex buffer object to use */ glBindBuffer(GL_ARRAY_BUFFER, gear->vbo); + /* Set up the position of the attributes in the vertex buffer object */ glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, - 6 * sizeof(GLfloat), NULL); + 6 * sizeof(GLfloat), NULL); glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, - 6 * sizeof(GLfloat), (GLfloat *) 0 + 3); + 6 * sizeof(GLfloat), (GLfloat *) 0 + 3); + + /* Enable the attributes */ glEnableVertexAttribArray(0); glEnableVertexAttribArray(1); - glDrawArrays(GL_TRIANGLE_STRIP, 0, gear->count); + + /* Draw the triangle strips that comprise the gear */ + int n; + for (n = 0; n < gear->nstrips; n++) + glDrawArrays(GL_TRIANGLE_STRIP, gear->strips[n].first, gear->strips[n].count); + + /* Disable the attributes */ + glDisableVertexAttribArray(1); + glDisableVertexAttribArray(0); } +/** + * Draws the gears. + */ static void gears_draw(void) { const static GLfloat red[4] = { 0.8, 0.1, 0.0, 1.0 }; const static GLfloat green[4] = { 0.0, 0.8, 0.2, 1.0 }; const static GLfloat blue[4] = { 0.2, 0.2, 1.0, 1.0 }; - GLfloat m[16]; + GLfloat transform[16]; + identity(transform); glClearColor(0.0, 0.0, 0.0, 0.0); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); - memcpy(m, proj, sizeof m); - rotate(m, 2 * M_PI * view_rotx / 360.0, 1, 0, 0); - rotate(m, 2 * M_PI * view_roty / 360.0, 0, 1, 0); - rotate(m, 2 * M_PI * view_rotz / 360.0, 0, 0, 1); - - draw_gear(gear1, m, -3.0, -2.0, angle, red); - draw_gear(gear2, m, 3.1, -2.0, -2 * angle - 9.0, green); - draw_gear(gear3, m, -3.1, 4.2, -2 * angle - 25.0, blue); + /* Translate and rotate the view */ + translate(transform, 0, 0, -20); + rotate(transform, 2 * M_PI * view_rot[0] / 360.0, 1, 0, 0); + rotate(transform, 2 * M_PI * view_rot[1] / 360.0, 0, 1, 0); + rotate(transform, 2 * M_PI * view_rot[2] / 360.0, 0, 0, 1); + + /* Draw the gears */ + draw_gear(gear1, transform, -3.0, -2.0, angle, red); + draw_gear(gear2, transform, 3.1, -2.0, -2 * angle - 9.0, green); + draw_gear(gear3, transform, -3.1, 4.2, -2 * angle - 25.0, blue); } -/* new window size or exposure */ +/** + * Handles a new window size or exposure. + * + * @param width the window width + * @param height the window height + */ static void gears_reshape(int width, int height) { - GLfloat ar, m[16] = { - 1.0, 0.0, 0.0, 0.0, - 0.0, 1.0, 0.0, 0.0, - 0.0, 0.0, 0.1, 0.0, - 0.0, 0.0, 0.0, 1.0, - }; - - if (width < height) - ar = width; - else - ar = height; - - m[0] = 0.1 * ar / width; - m[5] = 0.1 * ar / height; - memcpy(proj, m, sizeof proj); + /* Update the projection matrix */ + perspective(ProjectionMatrix, 60.0, width / (float)height, 1.0, 1024.0); + + /* Set the viewport */ glViewport(0, 0, (GLint) width, (GLint) height); } +/** + * Handles special eglut events. + * + * @param special the event to handle. + */ static void gears_special(int special) { switch (special) { - case EGLUT_KEY_LEFT: - view_roty += 5.0; - break; - case EGLUT_KEY_RIGHT: - view_roty -= 5.0; - break; - case EGLUT_KEY_UP: - view_rotx += 5.0; - break; - case EGLUT_KEY_DOWN: - view_rotx -= 5.0; - break; + case EGLUT_KEY_LEFT: + view_rot[1] += 5.0; + break; + case EGLUT_KEY_RIGHT: + view_rot[1] -= 5.0; + break; + case EGLUT_KEY_UP: + view_rot[0] += 5.0; + break; + case EGLUT_KEY_DOWN: + view_rot[0] -= 5.0; + break; } } static void gears_idle(void) { - static double tRot0 = -1.0; + static int frames = 0; + static double tRot0 = -1.0, tRate0 = -1.0; double dt, t = eglutGet(EGLUT_ELAPSED_TIME) / 1000.0; if (tRot0 < 0.0) @@ -322,37 +591,56 @@ if (angle > 3600.0) angle -= 3600.0; - eglutPostRedisplay(); + eglutPostRedisplay(); + frames++; + + if (tRate0 < 0.0) + tRate0 = t; + if (t - tRate0 >= 5.0) { + GLfloat seconds = t - tRate0; + GLfloat fps = frames / seconds; + printf("%d frames in %3.1f seconds = %6.3f FPS\n", frames, seconds, + fps); + tRate0 = t; + frames = 0; + } } static const char vertex_shader[] = - "uniform mat4 proj;\n" - "attribute vec4 position;\n" - "attribute vec4 normal;\n" - "varying vec3 rotated_normal;\n" - "varying vec3 rotated_position;\n" - "vec4 tmp;\n" - "void main()\n" - "{\n" - " gl_Position = proj * position;\n" - " rotated_position = gl_Position.xyz;\n" - " tmp = proj * normal;\n" - " rotated_normal = tmp.xyz;\n" - "}\n"; - - static const char fragment_shader[] = - //"precision mediump float;\n" - "uniform vec4 color;\n" - "uniform vec3 light;\n" - "varying vec3 rotated_normal;\n" - "varying vec3 rotated_position;\n" - "vec3 light_direction;\n" - "vec4 white = vec4(1.0, 1.0, 1.0, 1.0);\n" - "void main()\n" - "{\n" - " light_direction = normalize(light - rotated_position);\n" - " gl_FragColor = color + white * dot(light_direction, rotated_normal);\n" - "}\n"; +"attribute vec3 position;\n" +"attribute vec3 normal;\n" +"\n" +"uniform mat4 ModelViewProjectionMatrix;\n" +"uniform mat4 NormalMatrix;\n" +"uniform vec4 LightSourcePosition;\n" +"uniform vec4 MaterialColor;\n" +"\n" +"varying vec4 Color;\n" +"\n" +"void main(void)\n" +"{\n" +" // Transform the normal to eye coordinates\n" +" vec3 N = normalize(vec3(NormalMatrix * vec4(normal, 1.0)));\n" +"\n" +" // The LightSourcePosition is actually its direction for directional light\n" +" vec3 L = normalize(LightSourcePosition.xyz);\n" +"\n" +" // Multiply the diffuse value by the vertex color (which is fixed in this case)\n" +" // to get the actual color that we will use to draw this vertex with\n" +" float diffuse = max(dot(N, L), 0.0);\n" +" Color = diffuse * MaterialColor;\n" +"\n" +" // Transform the position to clip coordinates\n" +" gl_Position = ModelViewProjectionMatrix * vec4(position, 1.0);\n" +"}"; + +static const char fragment_shader[] = +"varying vec4 Color;\n" +"\n" +"void main(void)\n" +"{\n" +" gl_FragColor = Color;\n" +"}"; static void gears_init(void) @@ -364,6 +652,7 @@ glEnable(GL_CULL_FACE); glEnable(GL_DEPTH_TEST); + /* Compile the vertex shader */ p = vertex_shader; v = glCreateShader(GL_VERTEX_SHADER); glShaderSource(v, 1, &p, NULL); @@ -371,6 +660,7 @@ glGetShaderInfoLog(v, sizeof msg, NULL, msg); printf("vertex shader info: %s\n", msg); + /* Compile the fragment shader */ p = fragment_shader; f = glCreateShader(GL_FRAGMENT_SHADER); glShaderSource(f, 1, &p, NULL); @@ -378,6 +668,7 @@ glGetShaderInfoLog(f, sizeof msg, NULL, msg); printf("fragment shader info: %s\n", msg); + /* Create and link the shader program */ program = glCreateProgram(); glAttachShader(program, v); glAttachShader(program, f); @@ -388,31 +679,41 @@ glGetProgramInfoLog(program, sizeof msg, NULL, msg); printf("info: %s\n", msg); + /* Enable the shaders */ glUseProgram(program); - proj_location = glGetUniformLocation(program, "proj"); - light_location = glGetUniformLocation(program, "light"); - color_location = glGetUniformLocation(program, "color"); + + /* Get the locations of the uniforms so we can access them */ + ModelViewProjectionMatrix_location = glGetUniformLocation(program, "ModelViewProjectionMatrix"); + NormalMatrix_location = glGetUniformLocation(program, "NormalMatrix"); + LightSourcePosition_location = glGetUniformLocation(program, "LightSourcePosition"); + MaterialColor_location = glGetUniformLocation(program, "MaterialColor"); + + /* Set the LightSourcePosition uniform which is constant throught the program */ + glUniform4fv(LightSourcePosition_location, 1, LightSourcePosition); /* make the gears */ - gear1 = gear(1.0, 4.0, 1.0, 20, 0.7); - gear2 = gear(0.5, 2.0, 2.0, 10, 0.7); - gear3 = gear(1.3, 2.0, 0.5, 10, 0.7); + gear1 = create_gear(1.0, 4.0, 1.0, 20, 0.7); + gear2 = create_gear(0.5, 2.0, 2.0, 10, 0.7); + gear3 = create_gear(1.3, 2.0, 0.5, 10, 0.7); } int main(int argc, char *argv[]) { + /* Initialize the window */ eglutInitWindowSize(300, 300); eglutInitAPIMask(EGLUT_OPENGL_ES2_BIT); eglutInit(argc, argv); eglutCreateWindow("es2gears"); + /* Set up eglut callback functions */ eglutIdleFunc(gears_idle); eglutReshapeFunc(gears_reshape); eglutDisplayFunc(gears_draw); eglutSpecialFunc(gears_special); + /* Initialize the gears */ gears_init(); eglutMainLoop();