Demos (master): egl: Improve es2gears.c gears demo (version 2).
Chia-I Wu
olv at kemper.freedesktop.org
Thu Jul 15 03:07:14 UTC 2010
Module: Demos
Branch: master
Commit: 3feb7176cc6acc8dfc4e1e2a043bfc38c9189f5b
URL: http://cgit.freedesktop.org/mesa/demos/commit/?id=3feb7176cc6acc8dfc4e1e2a043bfc38c9189f5b
Author: Chia-I Wu <olvaffe at gmail.com>
Date: Thu Jul 15 10:18:48 2010 +0800
egl: Improve es2gears.c gears demo (version 2).
Improve GLES2 port:
* Refactor gear drawing.
* Use correct normals for surfaces.
* Improve shader.
* Use perspective projection transformation.
* Add FPS count.
* Add comments.
Patch from Alexandros Frantzis <alexandros.frantzis at linaro.org>.
---
src/egl/opengles2/es2gears.c | 655 ++++++++++++++++++++++++++++++------------
1 files changed, 478 insertions(+), 177 deletions(-)
diff --git a/src/egl/opengles2/es2gears.c b/src/egl/opengles2/es2gears.c
index 8e7a3e5..339613f 100644
--- a/src/egl/opengles2/es2gears.c
+++ b/src/egl/opengles2/es2gears.c
@@ -23,18 +23,23 @@
* Ported to GLES2.
* Kristian Høgsberg <krh at bitplanet.net>
* 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 <alexandros.frantzis at linaro.org>
+ * Jul 13, 2010
*/
-/*
- * Command line options:
- * -info print GL implementation information
- *
- */
-
-
#define GL_GLEXT_PROTOTYPES
#define EGL_EGLEXT_PROTOTYPES
+#define _GNU_SOURCE
+
#include <math.h>
#include <stdlib.h>
#include <stdio.h>
@@ -46,135 +51,239 @@
#include <EGL/eglext.h>
#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];
-
-static GLfloat *
-vert(GLfloat *p, GLfloat x, GLfloat y, GLfloat z, GLfloat *n)
+/** 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};
+
+/**
+ * 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;
+ 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;
}
-/* 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.
+/**
+ * Create a gear wheel.
*
- * 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
+ * @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 @@ multiply(GLfloat *m, const GLfloat *n)
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 @@ rotate(GLfloat *m, GLfloat angle, GLfloat x, GLfloat y, GLfloat z)
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 @@ translate(GLfloat *m, GLfloat x, GLfloat y, GLfloat z)
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
-draw_gear(struct gear *gear, GLfloat *m,
- GLfloat x, GLfloat y, GLfloat angle, const GLfloat *color)
+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
+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;
- 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);
+ deltaZ = zFar - zNear;
+ sincos(radians, &sine, &cosine);
+
+ if ((deltaZ == 0) || (sine == 0) || (aspect == 0))
+ return;
+
+ 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);
+ /* 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_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);
+ /* 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 @@ gears_idle(void)
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 @@ gears_init(void)
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 @@ gears_init(void)
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 @@ gears_init(void)
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 @@ gears_init(void)
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();
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