pass spheres to shader as array

shader/include/sphere.glsl

@@ -1,8 +1,6 @@
 struct Sphere
 {
-    vec3 center;
-    float radius;
+    // (c.x,c.y,c.z,r)
+    vec4 cr;
     vec3 albedo;
-    vec3 specular;
-    vec3 emission;
 };

shader/root/rt.glsl

@@ -1,5 +1,7 @@
 #version 430
 
+#include sphere.glsl
+
 // TODO: do i actually need explicit location descriptors?
 layout (location = 1)   uniform vec4 _t;
 
@@ -14,12 +16,15 @@ layout (location = 8)   uniform vec3 _camll;
 layout (location = 9)   uniform vec3 _cpos;
 layout (location = 10)  uniform vec3 _tpos;                     // target
 
+const int SPHERES = 250; // 253 is the maximum?? TODO: use uniform buffer objects
+layout (location = 12)  uniform int _activeSpheres;
+layout (location = 13)  uniform Sphere _spheres[SPHERES];
+
 layout(local_size_x = 1, local_size_y = 1) in;                  // size of local work group - 1 pixel
 layout(rgba32f, binding = 0) uniform image2D img_output;        // rgba32f defines internal format, image2d for random write to output texture
 
-const float INF = 30.0;
-
-#include sphere.glsl
+const float INF = 20.0;
+const float PI = 3.14159;
 
 struct Ray 
 {
@@ -37,9 +42,12 @@ struct RayHit
 
 void intersectSphere(Ray ray, inout RayHit bestHit, Sphere sphere)
 {
-    vec3 d = ray.origin-sphere.center;
+    vec3 c = sphere.cr.xyz;
+    float r = sphere.cr.w;
+
+    vec3 d = ray.origin-c;
     float p1 = -dot(ray.direction,d);
-    float p2sqr = p1*p1-dot(d,d)+sphere.radius*sphere.radius;
+    float p2sqr = p1*p1-dot(d,d)+r*r;
 
     if (p2sqr < 0) return;
 
@@ -49,7 +57,7 @@ void intersectSphere(Ray ray, inout RayHit bestHit, Sphere sphere)
     {
         bestHit.distance = t;
         bestHit.position = ray.origin + t*ray.direction;
-        bestHit.normal = normalize(bestHit.position-sphere.center);
+        bestHit.normal = normalize(bestHit.position-c);
         bestHit.albedo = sphere.albedo;
     }
 }
@@ -62,19 +70,6 @@ Ray createCameraRay(vec2 uv)
 
     vec3 target = vec3(0,0,0);
 
-    // transform camera origin to world space
-    // TODO: c2w matrix!! for now we just assume the camera is at the origin
-    // float3 origin = mul(_CameraToWorld, float4(0.0,0.0,0.0,1.0)).xyz;
-
-    // TODO: offset from centre of the lens for depth of field
-    // float2 rd = _CameraLensRadius * randomInUnitDisk();
-    // float3 offset = _CameraU * rd.x + _CameraV * rd.y;
-
-    // invert perspective projection of view space position
-    //vec3 dir = mul(_cameraInverseProjection, float4(uv, 0.0, 1.0)).xyz;
-
-    // TODO: transform direction from camera to world space (move camera around!)
-
     vec3 dir;
     dir = uv.x*_camh + uv.y*_camv;
     dir = _camll + uv.x*_camh + uv.y*_camv;
@@ -111,30 +106,10 @@ void main()
     hit.normal = vec3(0.0,0.0,0.0);
     hit.albedo = vec3(0.0,0.0,0.0);
 
-    vec3 spheresCenter = vec3(0.0,0.0,0.0);
-
-    float t = _t.x;
-    Sphere s1;
-    s1.center = spheresCenter+vec3(sin(t),0.0,cos(t))*2.5;
-    s1.radius = 2.0;
-    s1.albedo = vec3(1.0,0.0,0.0);
-
-    t+=3.1415/1.5;
-    Sphere s2;
-    s2.center = spheresCenter+vec3(sin(t),0.0,cos(t))*2.5;
-    s2.radius = 2.0;
-    s2.albedo = vec3(0.0,1.0,0.0);
-
-    t+=3.1415/1.5;
-    Sphere s3;
-    s3.center = spheresCenter+vec3(sin(t),0.0,cos(t))*2.5;
-    s3.radius = 2.0;
-    s3.albedo = vec3(0.0,0.0,1.0);
-
-    // ray-sphere intersection
-    intersectSphere(ray, hit, s1);
-    intersectSphere(ray, hit, s2);
-    intersectSphere(ray, hit, s3);
+    for (int i = 0; i < _activeSpheres; i++)
+    {
+        intersectSphere(ray, hit, _spheres[i]);
+    }
 
     // TODO: write depth to texture
     float depth = hit.distance/INF;

src/gfx.c

@@ -54,6 +54,10 @@ SDL_Window* gfxInit(int width, int height)
     glGetIntegerv(GL_MAX_VERTEX_ATTRIBS, &availableAttributes);
     printf("max vertex attributes %d\n", availableAttributes);
 
+    int uniformLocations;
+    glGetIntegerv(GL_MAX_UNIFORM_LOCATIONS, &uniformLocations);
+    printf("max uniform locations %d\n", uniformLocations);
+
     return sdlWindow;
 }
 

src/main.c

@@ -1,6 +1,8 @@
 #include "main.h"
 #include "gfx.h"
 
+#include "sphere.h"
+
 const int WIDTH = 420;
 const int HEIGHT = 420;
 
@@ -15,6 +17,8 @@ float time();
 void updateUniforms(GLuint shaderProgram);
 void updateCameraUniforms(GLuint shaderProgram);
 
+void updateSphereUniform(GLuint shaderProgram, struct Sphere sphere);
+
 int main()
 {
     // create a window and opengl context
@@ -62,6 +66,48 @@ int main()
     return 0;
 }
 
+void makeSpheres(struct Sphere *spheres, int count)
+{
+    float t = time();
+
+    vec3 albedos[] = 
+    {
+        {0.0,0.0,1.0},
+        {0.0,1.0,0.0},
+        {0.0,1.0,1.0},
+        {1.0,0.0,0.0},
+        {1.0,0.0,1.0},
+        {1.0,1.0,0.0},
+        {1.0,1.0,1.0}
+    };
+
+    // distance from center
+    float d = 6.0;
+    float radius = 0.5;
+    float x;
+    vec3 sc = {0.0,0.0,1.0};
+
+    for (int i = 0; i < count; i++)
+    {
+        x = t*0.1 + 2.0*CGLM_PI * i/(float)count;
+        sc[0] = sin(x)*d;
+        sc[2] = cos(x)*d;
+
+        float ic = i/(float)count;
+        float r = sin(ic);
+        float g = sin(ic+1.0);
+        float b = sin(ic+2.0);
+        g = 1.0;
+        b = 1.0;
+
+        vec3 col = {r,g,b};
+        glm_vec3_scale(col, 0.5, col);
+        glm_vec3_adds(col, 0.5, col);
+
+        spheres[i] = makeSphere(sc,radius,col);
+    }
+}
+
 void updateUniforms(GLuint shaderProgram)
 {
     float t = time();                                           // time
@@ -70,13 +116,19 @@ void updateUniforms(GLuint shaderProgram)
     glUniform4f(tLocation, t, sin_t, (1.0 + sin_t)*0.5, 0.0f);
 
     updateCameraUniforms(shaderProgram);
+
+    const int sphereCount = 42;
+    struct Sphere spheres[sphereCount];
+    makeSpheres(spheres, sphereCount);
+
+    updateSphereUniforms(shaderProgram, spheres, sphereCount);
 }
 
 void updateCameraUniforms(GLuint shaderProgram)
 {
     // set up perspective projection matrix and its inverse
     mat4 proj, proji;
-    float fovy = 60.0;                                          // vertical field of view in deg
+    float fovy = 90.0;                                          // vertical field of view in deg
     float near = 0.1;
     float far = 1000.0;
     float aspect = (float)WIDTH/(float)HEIGHT;
@@ -93,7 +145,8 @@ void updateCameraUniforms(GLuint shaderProgram)
 
     // lookat vector and view matrix
     float d = 10.0 + sin(t);
-    vec3 cpos = {sin(-t)*d,cos(0.5*t)*5.0,cos(-t)*d};                        // camera pos
+    float pt = -t*0.1;
+    vec3 cpos = {sin(pt)*d,cos(0.5*t)*5.0,cos(pt)*d};                        // camera pos
     vec3 tpos = {0.0,0.0,0.0};                                  // target pos
     glm_vec3_sub(cpos,tpos,cdir);                               // look dir (inverted cause opengl noises)
     glm_vec3_normalize(cdir); 
@@ -159,6 +212,7 @@ void updateCameraUniforms(GLuint shaderProgram)
     glUniform3f(camllLocation, camll[0], camll[1], camll[2]);
 }
 
+
 float time()
 {
     // ms / 1000.0 = seconds since start

src/sphere.c

@@ -0,0 +1,47 @@
+#include "sphere.h"
+
+struct Sphere makeSphere(vec3 center, float radius, vec3 albedo)
+{
+    struct Sphere s;
+
+    s.cr[0] = center[0];
+    s.cr[1] = center[1];
+    s.cr[2] = center[2];
+    s.cr[3] = radius;
+
+    glm_vec3_copy(albedo, s.albedo);
+
+    return s;
+}
+
+void updateSphereUniform(GLuint shaderProgram, struct Sphere sphere)
+{
+    int scrloc, saloc;
+    scrloc = glGetUniformLocation(shaderProgram, "_sphere.cr");
+    saloc = glGetUniformLocation(shaderProgram, "_sphere.albedo");
+
+    glUniform4fv(scrloc, 1, sphere.cr);
+    glUniform3fv(saloc, 1, sphere.albedo);
+
+    updateSphereUniforms(shaderProgram, &sphere, 0);
+}
+
+void updateSphereUniforms(GLuint shaderProgram, struct Sphere *spheres, int count)
+{
+    // set sphere count 
+    int loc = glGetUniformLocation(shaderProgram, "_activeSpheres");
+    glUniform1i(loc, count);
+
+    // each sphere takes up two uniform locations
+    const int stride = 2;         
+
+    // first location in the array
+    loc = glGetUniformLocation(shaderProgram, "_spheres[0].cr"); 
+
+    for (int i = 0; i < count; i++)
+    {
+        struct Sphere s = spheres[i];
+        glUniform4fv(loc+i*stride,   1,  s.cr);
+        glUniform3fv(loc+i*stride+1, 1,  s.albedo);
+    }
+}

src/sphere.h

@@ -0,0 +1,18 @@
+#pragma once
+
+#include <stdio.h>
+
+#define GLEW_STATIC
+#include <GL/glew.h>
+
+#include <cglm/vec3.h>
+
+struct Sphere
+{
+    vec4 cr;
+    vec3 albedo;
+};
+
+struct Sphere makeSphere(vec3 center, float radius, vec3 albedo);
+void updateSphereUniform(GLuint shaderProgram, struct Sphere sphere);
+void updateSphereUniforms(GLuint shaderProgram, struct Sphere *spheres, int count);

todo.md

@@ -7,10 +7,14 @@
     * [x] compile processed shaders
 * [-] render image with compute shader
     * [x] render a texture to a full-screen quad
-    * [x] pass uniforms to texture to animate it
+    * [x] pass uniforms to shader to animate it
+    * [x] pass structed uniform buffers
     * [-] ray tracing time
         * [x] perspective
         * [x] camera lookat
+        * [ ] do a bounce
+        * [ ] do a 'flect
+        * [ ] do a 'fract
         * [-] depth
             * [x] acquire value
             * [ ] depth texture