我想渲染地形并根据高度应用颜色 我正在写一个Qt项目,所以使用QGlShaderProgram。
我的地形网格从(0,0,0)到(1000,0,1000),顶点每100个长度单位放置一次。我想使用统一数组将数据传输到着色器。
我仍然无法向着色器发送数据。
从C ++ / Qt调用:
QGLShaderProgram mShader;
QVector< GLfloat> mHeightMap (10*10, some_data);
GLfloat mXStepSize = 100;
GLfloat mZStepSize = 100;
// ..
mShader.link();
mShader.bind();
mShader.setUniformValueArray( "heights",
&(mHeightMap[0]), // one line after another
mHeightMap.size(), 1 );
mShader.setUniformValue( "x_res", (GLint) mXStepSize);
mShader.setUniformValue( "z_res", (GLint) mZStepSize);
着色器来源:
uniform sampler2D heights;
uniform int x_res;
uniform int z_res;
void main(void)
{
vec4 tmp = gl_Vertex;
vec4 h;
float x_coord = gl_Vertex[0] * 0.001;
float z_coord = gl_Vertex[2] * 0.001;
// interprete as 2D:
int element = int( (x_coord + float(x_res)*z_coord) );
h = texture2D( heights, vec2(x_coord, z_coord));
gl_FrontColor = gl_Color;
gl_FrontColor[1] = h[ element]; // set color by height
tmp.y = h[ element]; // write height to grid
gl_Position = gl_ModelViewProjectionMatrix * tmp;
}
我的错误在哪里?
我应该如何将数据加载到着色器然后在那里访问它?
答案 0 :(得分:2)
您希望将其作为纹理传递,您必须首先使用glTexImage2D在opengl纹理中转换数组地图(mHeightMap)。 看看这个,它可能就是你要找的东西:https://gamedev.stackexchange.com/questions/45188/how-can-i-pass-an-array-of-floats-to-the-fragment-shader-using-textures
编辑:您可能想要调整一些,但这是理念:
//Create texture:
glint texture;
glActiveTexture(GL_TEXTURE0);
glGenTextures(1, &texture);
glBindTexture(GL_TEXTURE_2D, texture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, Width, Height, 0, GL_RGBA,
GL_UNSIGNED_BYTE, &(mHeightMap.constData()[data_start]));
//pass it to shader
glint uniformId = glGetUniformid(shader, "height");
glActiveTexture(GL_TEXTURE0);
glEnable(GL_TEXTURE_2D);
glBindTexture(GL_TEXTURE_2D, texture);
glUniform1i(uniformId, 0); // 0 is the texture number
答案 1 :(得分:2)
(代码似乎现在正常工作)
在izissise的帮助下,我想出了大部分内容。我使用了GL_TEXTURE_RECTANGLE而不是GL_TEXTURE_2D 它仍然只使用红色通道(这可能是优化的)。
这是我的初始化:
QGLShaderProgram mShader;
QVector< GLfloat> mHeightMap (width * height * state_count,
some_data);
mShader.link();
// init texture
glActiveTexture(GL_TEXTURE0);
glGenTextures(1, &mShaderTexture);
glBindTexture(GL_TEXTURE_RECTANGLE, mShaderTexture);
并且将数据发送到着色器(这可以根据需要重复):
mShader.bind();
// ..
glTexImage2D(GL_TEXTURE_RECTANGLE, 0, GL_RED,
width, depth, 0,
GL_RED, GL_FLOAT,
&(mHeightMap.constData()[mHeightMapPos])); // set portion of vector as array to texture / sampler
glActiveTexture(GL_TEXTURE0);
glEnable(GL_TEXTURE_RECTANGLE);
glBindTexture(GL_TEXTURE_RECTANGLE, mShaderTexture);
mShader.setUniformValue( "max_height", (GLfloat) (250.0) );
mShader.setUniformValue( "x_steps", (GLint) width);
mShader.setUniformValue( "z_steps", (GLint) height);
// ..
mShader.release();
以及着色器源:
uniform int x_steps;
uniform int z_steps;
uniform sampler2DRect heights;
uniform float max_height;
void main(void)
{
vec4 tmp = gl_Vertex;
vec4 h;
float x_coord = gl_Vertex[0] * 0.001 * float(x_steps-1);
float z_coord = gl_Vertex[2] * 0.001 * float(z_steps-1);
h = texture2DRect( heights, ivec2(int(x_coord), int(z_coord)) );
tmp.y = max_height * (h.r);
gl_FrontColor = gl_Color;
gl_FrontColor[1] = h.r;
gl_Position = gl_ModelViewProjectionMatrix * tmp;
}